Multiprocessing Process error when restart in python 2.7

Question

What do you think is wrong with the following code?

from multiprocessing import Process as multicore  

class tbe_worker(multicore):  
    def __init__(self):  
        multicore.__init__(self)  
        print "init tbe_worker"  

    def run(self):  
        print "run tbe_worker"  

class Main:  
    def __init__(self):  
        self.w_tbe = tbe_worker()  
        print self.w_tbe  
        print "create w_tbe instance"  

    def startelab(self):  
        print "start thread"  
        print "alive:", self.w_tbe.is_alive()  
        print self.w_tbe  
        self.w_tbe.start()  
        print "after start"  
        print self.w_tbe  

    def stopelab(self):  
        print "alive:", self.w_tbe.is_alive()  
        print "exitcode:", self.w_tbe.exitcode  
        if self.w_tbe.is_alive():  
            print "alive:", self.w_tbe.is_alive()  
            self.w_tbe.terminate()  
            print "alive:", self.w_tbe.is_alive()  
        self.w_tbe.join()  
        print "alive:", self.w_tbe.is_alive()  
        print self.w_tbe  

    def run(self):  
        print "before main run"            
        while True:  
            x = raw_input()  
            if x == "v":  
                self.startelab()  
            else:  
                self.stopelab()  
        print "after main run"  

if __name__ == '__main__':  
    Main().run()  

If I do the following actions:

• initialize the process
• start the process -> (the process ends immediately)
• verify that the process is finished and do the join ()
• restart the process

This is the output of the test:

init tbe_worker
<tbe_worker(tbe_worker-1, initial)>
create w_tbe instance
before main run
v
start thread
alive: False
<tbe_worker(tbe_worker-1, initial)>
after start
<tbe_worker(tbe_worker-1, started)>
run tbe_worker
c
alive: False
exitcode: 0
alive: False
<tbe_worker(tbe_worker-1, stopped)>
v
start thread
alive: False
<tbe_worker(tbe_worker-1, stopped)>

I get this error:

File "C:/Program Files/Python27x64/lib/multiprocessing/process.py", line 120,
in start
    assert self._popen is None, 'cannot start a process twice'
AssertionError: cannot start a process twice
Press any key to continue . . .

It may be that the process can not start more than once after completion and termination of the same? If so, do I have to create a new process each time you want to start a new job? (It seems strange thing)
But above all, it only happens to me? Because on the web I find no argument about it.
There is definitely something I'm missing, but I can not figure out what ...

Answer 1

From multiprocessing documentation.

start()

Start the process’s activity.

This must be called at most once per process object. It arranges for the object’s run() method to be invoked in a separate process.

If you want to launch again your target function, you need to create a new Process object. Process objects are unique and their lifecycle is bound to the process themselves.